Roger Gates: Monitoring end of season grasslands
Fall is an excellent time to evaluate the results of management decisions implemented during the growing season. Season-ending grassland conditions reflect the impact of environmental conditions on plant growth and the modifying effects of timing, duration and intensity of grazing on plant growth and recovery.
Good managers will make the effort during autumn to evaluate the “energy status” of the grazinglands they manage. In a manner similar to body condition scores assigned to the cowherd, vegetation and landscape conditions at the end of the growing season indicate what happened during the grazing season. End of season status provide more than just recent history; it also can serve as a leading indicator of future productivity.
On one extreme, pasture defoliated by severe, season long grazing is easy to “condition score” and will be less productive during the following year. On the other extreme and perhaps almost as easy to evaluate are pastures that remained ungrazed, receiving a full growing season deferment. These pastures will be more productive during the coming growing season. Parenthetically, the parallel to excessively fat cows might be those pastures that have remained ungrazed for several consecutive years. While periodic rest benefits pasture vegetation, excessive rest is “abnormal” and compromises overall productivity and composition of the vegetation community.
Just as fat cover serves as an accurate indicator of a cow’s energy status, residual vegetation reflects the “energy status” of grazingland plants. Sunlight is the energy source for green plants. Grasses and forbs must be allowed an adequate opportunity to display their leaves in order to develop energy reserves. Sunlight “harvested” during the growing season is converted into plant tissue, providing for growth and grazable feed. Particularly at the end of the growing season, plants that are in a positive energy balance are able to partition energy to storage organs such as stem bases, stolons, rhizomes and roots. Stored nutrients are critical to winter survival and initial spring growth.
For many cool-season grasses, new tillers initiated from buds in the fall establish the threshold for potential production beginning the following spring. Residual vegetation or stubble height reflects the opportunity pasture plants have had to establish and maintain a positive energy budget and therefore is a suitable leading indicator for next year’s production.
Time spent evaluating your grazing resources this fall, pasture by pasture, is the first step in developing appropriate grazing plans for next year. Pastures with limited residual vegetation should be given the opportunity for plants to develop and display their leaves for the longest period of time next season. The most beneficial management intervention would be to delay grazing until the growing season is completed. Conversely, those pastures where residual vegetation displays the most positive energy status are likely to be most productive and could be grazed earliest next year.
Two cardinal rules, often applied to range management, are always appropriate: “take half and leave half,” and “never graze the same pasture at the same time two years in a row.” Both guidelines will provide for positive energy balance and improving condition scores for the grazinglands you manage. Take the time to make a careful pasture inventory this fall and use that information to guide your grazing plans for next year.
In addition to evaluation of short-term management impacts, the end of the growing season is a prime opportunity to commit time to longer-term monitoring. The best “return on investment” is likely to come from establishing photo points. The objective of long-term monitoring is to provide a record of landscape change. This generally is extremely slow on grasslands. Our memories are not sufficient to provide the kind of recall that is needed to evaluate long-term change. Precise and quantitative procedures are available to monitor change, particularly the species composition of pastures that will reflect long-term grazing trends. However, photo points can provide an extremely valuable qualitative record of landscape conditions. Without a permanent record, evaluating the long-term impact of grazing management decisions is much more difficult and reduces the confidence with which future plans can be developed.
Enjoy the cooling temperatures and take the time to evaluate the results of this year’s grazing plan. It’s the best first step to making plans for grazing this winter and next year.
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